1. Field Of The Invention
The present invention relates generally to the field of securement structures for aligning terminal blocks, input/output devices and other electrical components within enclosures and the like. More particularly, the invention relates to a self-locking, clip-in structure that can easily and quickly be mounted on a standard support rail, and that can be adapted for use as a terminal block or other device support.
2. Description Of The Related Art
A number of systems have been developed and are currently in use for mounting small components, particularly electrical components, in enclosures. Such systems include various conduit and rail structures useful for channeling wires to and from the components in a neat and orderly manner, facilitating installation and servicing. One popular system of this type is based upon a standard set of flanged rails that can be cut to a desired length and attached via screws to the interior of an enclosure. The rails, commonly referred to as "DIN" rails, have either inwardly or outwardly projecting raised flanges along their length for receiving the components. The components, including a wide array of modular elements such as terminal blocks, input/output modules, dip switches, and so forth, feature corresponding structures designed to interface with the rail flanges to hold the components securely in place during installation and use.
Known component mounting structures include screw-down and screwless styles. Screw-down structures generally clip into place along the DIN rail and may be slid along the rail for positioning. A screw held over one of the rail flanges is then driven into the flange to anchor the component in place. In addition to the cost of the screw and associated holding elements, a disadvantage of these structures is the need to independently secure each component via the screw. This process is not only time consuming, but may result in misalignment on the rail due to twisting of the component under the influence of the screw-down torque. In many applications, therefore, the screwless mounting arrangements are often preferable. These arrangements typically include a component module having a hook-shaped rigid foot that is slipped over a first of the rail flanges, and a deformable leg that is then snapped over the opposite flange to secure the component to the rail. Because the modules are typically made of a moldable plastic material due to its good electrical insulation capabilities, metallic clips and the like are often provided in the rail interface features to bind the component more securely in place on the rail. For removal, the deformable leg may be bent free of the rail flange and the component may be removed by unhooking the rigid foot from the opposite flange.
While such known screwless DIN rail mounting structures provide an attractive solution to the problem of quickly and easily attaching components in desired rail locations, they are not without drawbacks. For example, known arrangements of this type employ differently configured metallic securing elements on either side of the module. These elements must be added to the molded module during an assembly process, such as by heat staking. A first obvious drawback, then, results from the number of separate, different parts in the resulting assembly and the number of operations required to produce the final product. In addition, the metallic features typically include only three to five separate points of contact with the rail flanges. Because the force resisting movement of the component along the rail is generally a function of the number of contact point and the holding force exerted at each point, substantial spring force is often required in the deformable leg to attain the desired holding force, making the structure more difficult to snap into place and to remove from the rail. Moreover, due both to the different interface features and to the substantial spring force in conventional devices, the user must generally attach the module in a prescribed order (i.e., rigid foot first, then the deformable leg).
There is a need, therefore, for an improved arrangement for mounting components along DIN rails. The arrangement should be of a straightforward design that can be easily manufactured and assembled on the rail. In particular, there is a need for a DIN rail mounting structure that provides superior holding force while minimizing the number of different parts in the overall product.